The factors affecting the deflection of a cantilever when weights are added onto the end.

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Physics Investigation

I am trying to find out about:

The factors affecting the deflection of a cantilever when weights are added onto the end.

What I think will happen:

I think that as the weights are added to the cantilever, the deflection will increase.

I think this will happen because:

I think the deflection will increase because gravity will push down on the cantilever and weights while the atoms in the cantilever will be resisting this force: -

I know that MOMENT = FORCE(N) X DISTANCE

This means that the moment of the weights is the distance from the bench (or pivot) multiplied by the number of Newtons attached to the hook. As I know that the moment increases as more weight is added, I can use this to back-up my prediction by stating that more weight (or moment) causes more deflection e.g. I predict that weight is directly proportional to deflection. This could also be likened to a bimetallic strip, which will bend more as it is increasingly heated or cooled.

The atoms in a solid are rather like a spring in that if they are stretched, they will try to return to their original position when released (unless stretched beyond their elastic limit). An example is a cube (see next page):

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When one atom is pulled, any atoms connected to this atom will try to pull each other back into their original shape.

The atoms in the cantilever are being stretched so that the beam deflects downwards. The top of the cantilever gets stretched (called tension) and the bottom of the cantilever gets squashed (called compression). A cantilever that has a high cross-section will bend less than one with a low cross-section. This means that as more weight is added to the cantilever, the more tension and compression there will be. I think the atoms at the middle of the ...

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